This invention relates to systems and methods of increasing the binding strength of a bound text body.
Today, a variety of different bookbinding systems can deliver professionally bound documents, including books, manuals, publications, annual reports, newsletters, business plans, and brochures. A bookbinding system generally may be classified as a commercial (or trade) bookbinding system that is designed for in-line manufacturing of high quality volume runs or an in-house (or office) bookbinding system designed for short xe2x80x9con-demandxe2x80x9d runs. Commercial bookbinding systems generally provide a wide variety of binding capabilities, but require large production runs (e.g., on the order of thousands of bindings) to offset the set-up cost of each production run and to support the necessary investment in expensive in-line production equipment. Office bookbinding systems, on the other hand, generally involve manual intervention and provide relatively few binding capabilities, but are significantly less expensive to set up and operate than commercial bookbinding systems, even for short on-demand production runs of only a few books.
In general, a bookbinding system collects a plurality of sheets (or pages) into a text body (or book block) that includes a spine and two side hinge areas. The bookbinding system applies an adhesive to the text body spine to bind the sheets together. A cover may be attached to the bound text body by applying an adhesive to the side hinge areas or the spine of the text body, or both. The cover of a typical commercial soft cover book generally is attached to the text spine. The covers of hardcover books and some soft cover xe2x80x9clay flatxe2x80x9d books, on the other hand, typically are not attached to the text body spines (i.e., the spines are xe2x80x9cfloatingxe2x80x9d).
Many different systems have been proposed for applying adhesive to a text body spine to bind the text body sheets together.
For example, U.S. Pat. No. 5,346,350 discloses an apparatus for binding sheets that includes an aligning plate that aligns the sheets edges at the spine edge, and two clamping plates that hold the sheets during binding. A heating platen heats and melts a backless solid hot melt adhesive that is placed along the sheet edges. The hot melt adhesive binds the sheets together at the spinal area. According to the ""350 patent:
Capillary action is the preferred primary mechanism by which the adhesive flows into the stack 12 to bond the paper sheets together. Capillary action assists both the adhesion of the adhesive material 94 to the stack of paper 12 and the internal cohesion within the adhesive material 94.
Additionally, the platen 120 of the heating subsystem 118 does not push the adhesive 94 into the edge 13 of the stack 12. Ideally, the platen 120 applies zero pressure against the stack 12 and only contacts the adhesive material sheet 94 sufficiently to melt the adhesive 94 so that the gravity-assisted capillary action causes the liquid adhesive 94 to wick into and bond the stack 12 together. Putting pressure on the adhesive 94 in an attempt to push it into the stack 12, whether pushing downwardly, upwardly, or sideways, would not enhance bonding. Rather, this would squeeze the adhesive off of the edge 13 and off of the stack 12 through the sides between the platen 120 and the stack 12 and defeat the effects of capillary action. Thus, the platen is designed to apply only minimal pressures on the edge 13 of the stack 12 to maintain contact between the platen 120, the adhesive 94 and the stack 12.
(Col. 8, line 60 through col. 9, line 29)
The hot melt adhesive also may be used to attach a preformed book cover to the text body spine.
International Patent Publication No. WO 99/38707 discloses a paperback bookbinding scheme in which a cover with an adhesive strip disposed along a spine area is forced between a pair of pressing rollers to form a pocket, and a text body is inserted into the pocket with the text body spine in contact with the adhesive strip. The pressing rollers are moved forcibly toward one another to compress the cover firmly against the front and back sides of the text body and to compress the text body sheets together tightly in the area adjacent to the spine. A sonic tool transmits sonic energy to the cover to activate the adhesive strip and, thereby, bind the text body sheets and the cover into a perfectly bound book.
U.S. Pat. No. 4,911,475 discloses a bookbinding construction in which sheets are bound together into a book block by two or more spaced-apart transverse segments of adhesive. The front section of a cover is attached to the first page of the book block and the back section of the cover is secured to the last page of the book block. Upon opening the book or turning a page, glue-free portions of the spine edge of the open page flex or bow outward over the facing page in a wedging manner or interfering fit. According to the ""475 patent, this wedging action against the opposite page resists the tendency of the book to spring closed and forces the pages of the book to lie flat.
U.S. Pat. No. 5,271,794 discloses an adhesive applicator that is configured to spread coat an adhesive onto the spine and side edges of a text body to bind the text body sheets and a cover into a perfectly bound book with an attached spine. The adhesive applicator includes a book spine coating nozzle with adjustable side sealing jaws for adjusting the nozzle width for different book thicknesses and separate side glue outlets for depositing glue on the book sides. Glue flow control valves are disposed between the spine coating nozzle and the side glue outlets so the glue deposited on the book sides may be selectively and independently cut off or controlled.
Still other bookbinding systems have been proposed.
The invention features novel systems and methods of increasing the binding strength of a bound text body.
In one aspect, the invention features a method of binding sheets into a bound text body in accordance with which a text body is formed from a number of sheets characterized by a height dimension and a thickness dimension. An adhesive is applied to a spine of the text body to bind the sheets into a bound text body. The text body has a surface area exposed for adhesive penetration that is greater than an area corresponding to the product of the sheet height dimension, the sheet thickness dimension and the number of sheets.
Embodiments in accordance with this aspect of the invention may include one or more of the following features.
The text body may be formed by registering the sheets with respect to two datum edges so that variations in sheet width dimension are accommodated in the spine of the text body.
In some embodiments, the text body is formed by processing sheets to increase the surface area exposed for adhesive penetration along the spine of the text body. The sheets may be processed by embossing sheet edges corresponding to the spine of the text body, and the sheets preferably are collected in a sequence with alternate sheets embossed at the spine end of the text body. The sheets may be processed by forming sheets with non-linear edges at the spine of the text body. The non-linear sheet edges may be characterized by periodic variations along the spine of the text body. The text body may be formed by collecting sheets in a sequence and sheets may be processed by forming adjacent sheets with different width dimensions. The sheets may be processed by perforating sheets along respective fold lines corresponding to the spine of the text body and folding sheets along the fold lines.
In some embodiments, the sheets are processed by separating adjacent sheets as adhesive is applied to the spine of the text body. Adjacent sheets may be separated by clamping the text body at one or more locations near the spine of the text body. Adjacent sheets may be separated by applying across the spine of the text body a force directed along a thickness dimension of the text body. The force may be applied by a flow of air directed across the spine edge of the text body or by a rotary mechanism. Adjacent sheets also may be separated by applying to the adhesive a force driving adhesive between adjacent sheets.
In another aspect of the invention, a system for binding sheets into a bound text body includes a sheet collector and an adhesive applicator. The sheet collector is configured to form a text body from a number of sheets characterized by a height dimension and a thickness dimension. The text body has a surface area exposed for adhesive penetration that is greater than an area corresponding to the product of the sheet height dimension, the sheet thickness dimension and the number of sheets. The adhesive applicator is configured to apply to a spine of the text body an adhesive for binding the sheets into a bound text body.
Embodiments in accordance with this aspect of the invention may include one or more of the following features.
The sheet collector may be configured to register the sheets with respect to two datum edges so that variations in sheet width dimension are accommodated in the spine edge of the text body.
The sheet collector may be configured to process sheets to increase the surface area exposed for adhesive penetration along the spine of the text body. For example, the sheet collector may be configured to emboss sheet edges corresponding to the spine end of the text body. In some embodiments, the sheet collector is configured to separate adjacent sheets as adhesive is applied to the spine of the text body.
Other features and advantages of the invention will become apparent from the following description, including the drawings and the claims.